Departed from port (4)
I believe the answer is:
left
I believe this is a double definition.
'departed' is the first definition.
(to leave is to depart)
'port' is the second definition.
(port is the left side on a boat)
'from' acts as a link.
(Other definitions for left that I've seen before include "Sailed from" , "Facing north, it's the side toward the west" , "choice at a junction?" , "Departed - port" , "Vacated; political wing" .)